Recovery of zinc from electric arc furnace dust by alkaline pressure leaching using iron as a reductant

碱性加压浸出体系中铁粉还原浸出电弧炉烟尘中锌的工艺研究

To recover zinc from electric arc furnace(EAF)dust,a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed.First,under the alkaline pressure leaching system,the experiment of pure zinc ferrite being reduced by iron powder was carried out.Under the optimal reduction conditions(i.e.,temperature of 260℃,NaOH concentration of 6 mol/L,liquid-to-solid ratio of 50 mL/g,and a 5-fold excess of iron powder),89%of zinc was extracted.The iron in the reduced residue exists as a magnetite phase.Subsequently,the normal pressure leaching experiment was carried out with EAF dust as raw material,and 66%zinc was leached.The main phase of zinc in normal leaching residue was determined to be zinc ferrite.Then,the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system,and 66.5%of zinc was extracted.After the two-stage leaching process,the leaching rate of zinc in EAF dust can achieve 88.7%.The alkaline pressure leaching solution can be returned as the normal pressure leaching solution,and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.

为了从电弧炉烟尘中回收锌,本文提出了一种常压浸出与碱性加压浸出结合的工艺。首先,在碱性加压浸出体系下,进行了铁粉还原纯铁酸锌的实验,确定了温度260℃、NaOH浓度6 mol/L、液固比50 mL/g、铁粉过量系数为5的最佳还原条件,在此条件下锌的浸出率为89%,还原渣中铁以磁铁矿物相存在。随后,以电弧炉烟尘为原料,进行了常压浸出实验,实现了原料中66%锌的浸出,并确定了常压浸出渣中锌的主要物相为铁酸锌。接着,对常压浸出渣进行了碱性加压浸出体系铁粉还原浸出,实现了常压浸出渣中66.5%的锌被浸出。两段浸出可实现电弧炉烟尘中88.7%的锌进入浸出液中,同时碱性加压浸出液可返回作为常压浸出液,并通过磁选的方法回收中碱性加压浸出渣的磁铁矿。